Spectral Line Surveys with the CSO Susanna L. Widicus Weaver, Department of Chemistry, Emory University Matthew Sumner, Frank Rice, Jonas Zmuidzinas, Department of Physics, Caltech Geoffrey Blake, Department of Geological & Planetary Sciences, Department of Chemistry, Caltech

The Widicus Weaver Group Mary Radhuber Jay Kroll Brandon Carroll Jake Laas Thomas Anderson

New Receiver Technology at the CSO “Z-Rex” receiver designed for external galaxy searches at high-z Broad frequency coverage High S/N Double sideband (DSB) receiver Facility CSO ReceiversZ-Rex T sys (K, SSB) Spectral (IF) Bandwidth (GHz) 1 4 Z-Rex is an ideal receiver for spectral line surveys!

What is a Line Survey? Typical Observations Individual, narrow frequency windows targeting only a handful of transitions. Line Survey A series of spectral windows pieced together to provide spectral coverage across a large frequency range.

Why Line Surveys? More lines observed more detection certainty Uniform coverage under similar instrument conditions minimizes calibration inconsistencies Comprehensive intensity information reliable model of physical conditions Broadband spectral coverage large amounts of info, and fast

Why New Molecular Line Surveys? Our Goals: Conduct surveys for many different types of sources Achieve high spectral sensitivity (for new molecule ID) Obtain full picture of chemical, physical conditions for each source Compare results to astrochemical models New astrochemical models explain formation of complex organics Models require complete chemical, physical picture for input/comparison Physical parameters, abundances often educated guesses Few surveys access differing chemical, physical environments Garrod, Widicus Weaver, & Herbst, ApJ 682, 2008

The Orion KL Region Orion KL star forming region timedial/bilderWissenschaft/2009/02/Walter0902/ Web_Zoom.jpeg From Liu, S.-Y. et al. (ApJ 576, 2002) CSO Beam Size at  = 1 mm

Previous Orion KL Surveys >50 radio frequency Orion spectral line surveys reported in the literature! OVRO survey at = 1.3 mm 215 – 263 GHz RMS~ 150 mK 800 resolved spectral features 29 molecular species IDed

The Challenge: DSB Spectra + = Image sideband Observed Double Sideband Spectrum Frequency sideband desired line position Spectra from Nummelin et al. (ApJ Supp. Series 117, 1998) Lower SidebandUpper Sideband -IF +IF LO

Spectral Coverage on Orion

Initial Deconvolution of Orion Spectra Blake et al. OVRO survey: RMS = 150 mK, integration time ~ weeks (months?) Our survey: RMS = 30 mK, time ~ 4 nights

Line Identification Progress Total Lines >3  5548 Assigned Lines (to date)662 (11.9%) Unidentified Lines4886 (88.1%) Lines Assigned in Previous Surveys400 New Lines Assigned (to date)262

Line Identification Progress MoleculeLines Previously ObservedNew Lines Observed CO20 DNC10 C 17 O10 H 2 CO10 CH 3 CCH50 CH 3 13 CN20 HNCO30 C 33 S10 HDO21 CN111 CH 3 CN CS11 C 34 S11 H 2 CS72 13 CH 3 CN73 CH 2 CO45 HCOOH76 C 2 H 5 CN6022 CH 3 OH CH 3 OH1142 CH 3 CHO446 CH 3 OCH

Line Identification

Next Steps? Orion Survey Analysis Finalize spectral deconvolution incorporate baseline subtraction, test for “ghosts” Analyze spectral information determine lineshapes, intensities Identify more lines from previously detected molecules include weak lines, isotopologues, vibrational states Rotational diagram analysis for each molecule account for multiple sources, velocities, temperatures Beyond the Orion Survey Line surveys of other sources completed: Sgr B2(N-LMH), NGC 1333-IRAS 4, L1157 upcoming: W51 e1/e2, G , W3(H 2 O) & W3(OH) Laboratory spectroscopic studies Comparison to astrochemical models ID of new molecules only after complete simulation of known molecules is achieved

1 – 50 GHz Frequency Synthesizer VDI Multiplier chain 50 GHz – 1.2 THz Detector Gas Flow Cell To Computer Sample InputTo Vacuum Pump Laboratory Spectral Cataloging Methanol Broadband Scan Dimethyl Carbonate (CH 3 OCOOCH 3 ) First light April 1, 2009!

Acknowledgements The Widicus Weaver Group: Mary Radhuber Jay Kroll Brandon Carroll Jake Laas Thomas Anderson John Pearson & Brian JPL CSO Local Staff